A119

A-119 External Input / Envelope Follower



Mods

Change the TL064 Op-Amp for an TL074 (will use slighly more power). The TL064 is just a low power version of the TL074 and it is 3 times noisier. (there are two chips on the board, one is a LM324 for the envelope follower) This are socketed chips, so just pull the old one and plug the new one in. See the threads for detailed discussion.

Use

asym., unbalanced line input up to 20x amplification

symm., balanced (microphone) input up tp 500x amplification.

Both inputs are summed up. Using the gain, both inputs are amplified (mix 1:25). If you are using the line in you also sum the internal noise of the balanced input (amplified with gain) to your signal. The line in also has a high-frequency attenuation.

The balanced input is not built only for microphones, it has a relatively high self capacitance of 47 kOhm, so is also useable for line input. And you can also use a simple unbalanced cable (a regular mono cable)  with the "balanced" input.

So use the balanced input also for line signals, you will only need slightly gain then which will keep also the noise down. See the threads for detailed discussion and those 2 threads in german from where this mainly is: http://www.sequencer.de/synthesizer/viewtopic.php?p=252422, http://www.sequencer.de/synthesizer/viewtopic.php?p=253557

Threads

[http://muffwiggler.com/forum/viewtopic.php?t=5163 Pimp my A-119? ]

[http://muffwiggler.com/forum/viewtopic.php?t=13208 external/line inputs: a119 vs. rs70? ]